NNN Lease Calculator

A triple net lease structure allocates three categories of operating cost to the tenant in addition to base rent: real estate taxes, property insurance, and common area maintenance, commonly abbreviated CAM. This differs from a gross lease, where the landlord pays all operating expenses out of the quoted rent, and from a modified gross lease, where some expenses are shared or capped. In an absolute or bondable NNN lease, sometimes used for single-tenant retail and industrial buildings, the tenant may even be responsible for roof and structure, though that is unusual in multi-tenant properties.

The two figures a tenant sees on a term sheet are base rent per square foot per year and estimated NNN charges per square foot per year, sometimes called additional rent or the operating expense estimate. Multiplying each by rentable square feet and dividing by twelve gives the monthly base rent and monthly NNN payment; adding them gives the total monthly rent the tenant actually writes a check for. A tenant leasing 10,000 square feet at $22 base and $7.50 NNN pays $22,916.67 in base rent and $6,250.00 in NNN charges each month, for $29,166.67 total, before any escalation.

CAM charges themselves are a pass-through of the landlord's actual costs: parking lot repair, landscaping, common utilities, property management fees, and often a management fee markup of 10% to 15% on top of actual costs. Tenants should always request an annual CAM reconciliation right, which lets them audit the landlord's actual expenses against the estimate they were billed monthly and recover any overcharge.

Because NNN charges are reconciled annually against actual costs, the figure quoted at lease signing is always an estimate. Experienced tenants budget 5% to 10% above the initial NNN quote to absorb reconciliation true-ups, particularly in the first full year of occupancy when landlords sometimes underestimate deliberately to make a deal look more attractive.

Base rent in a multi-year commercial lease almost never stays flat. The two most common structures are fixed annual escalations, typically 2% to 4% per year, and periodic step-ups, such as a flat rent for years one through three followed by a fixed increase in year four. Some leases index rent to CPI, though CPI-based escalations became less common after the inflation spike of 2021 to 2023 pushed landlords toward fixed steps that are easier for both parties to underwrite.

Compounding matters more than tenants often expect. A $22.00 base rent escalating 3% annually for ten years reaches roughly $28.72 by year ten, not $28.60 as a simple 3% times ten calculation would suggest, because each year's increase applies to the prior year's already-escalated rent. Over a ten-year term, the average annual base rent paid, weighted evenly across the term, comes out meaningfully higher than the starting rent quoted in the marketing flyer.

This is exactly why brokers and appraisers rely on effective rent rather than starting rent to compare deals. Effective rent per square foot averages the total base rent obligation over the full term, net of free rent, and expresses it as a single annualized number. Two spaces quoted at the same $22.00 starting rent can have meaningfully different effective rents once one includes six months of free rent and 4% annual bumps while the other includes no free rent and 2.5% bumps.

For NNN charges, most underwriting holds the pass-through estimate flat or escalates it at a modest 2% to 3% per year to reflect rising taxes and insurance, since CAM is a reimbursement of actual cost rather than a negotiated rent number. Property tax reassessments after a sale, sometimes 20% to 40% higher than the prior owner's basis, are a common source of a large NNN jump in year two of a new ownership.

Free rent, also called an abatement period, is a concession where the tenant pays no base rent (and sometimes no NNN) for an agreed number of months, typically at the start of the term. It is standard in new leases to offset the tenant's move-in costs and downtime, and it scales with term length and market softness: a five-year office lease might see one to three months free, while a ten-year lease in a soft market can see six months or more.

A tenant improvement allowance, or TI allowance, is a dollar amount per square foot the landlord contributes toward build-out: new flooring, partitions, paint, ceiling grid, and similar work. Office TI allowances in most US secondary and primary markets in the mid-2020s run from $20 to $80 per square foot for a second-generation space, and $80 to $150 or more for a raw shell, with retail and industrial TI generally lower, often $5 to $25 per square foot given simpler build-outs.

Both concessions cost the landlord real money that never shows up in the headline rent, which is why landlord net effective rent is the number that matters for underwriting and for comparing competing lease proposals on the same building. It is computed by taking the total base rent collected over the term, subtracting the value of free rent and the tenant improvement allowance, and dividing by square footage and by the number of years in the term to get a net effective figure per square foot per year.

Consider a 10,000 square foot, ten-year lease at $22.00 base rent with 3% annual escalations, three months of free rent, and a $15.00 per square foot TI allowance. Gross base rent collected over the term is roughly $2,522,000. Free rent costs about $57,300 in foregone rent, and TI costs $150,000. Net proceeds to the landlord are about $2,314,700, or roughly $23.15 per square foot per year net effective, versus the $22.00 headline starting rent — in this case the escalations more than offset the concessions, which is common on longer terms but is never guaranteed on shorter ones.

Landlords use this net effective figure to decide how much concession they can afford while still hitting a required return, and lenders use it to sanity check the rent roll a borrower is presenting for refinance, since a rent roll full of unamortized free rent and TI overstates the durable cash flow of the asset.

Single-tenant net lease retail, the format used for pharmacy, quick-service restaurant, and dollar-store ground leases, typically runs 10 to 25 year primary terms with multiple renewal options, fixed 1% to 2% annual or 5% to 10% every-five-year escalations, and cap rates in the 5.5% to 7.5% range for investment-grade credit tenants as of the mid-2020s. These are frequently absolute net, meaning the tenant handles roof and structure as well.

Multi-tenant retail and neighborhood shopping centers commonly use standard triple net terms of five to ten years, CAM reconciled annually, and base rent in the $15 to $35 per square foot range depending on market, with anchor tenants often paying less per square foot than in-line shop tenants under a different rent structure entirely.

Industrial and warehouse NNN leases have compressed base rent, often $5 to $12 per square foot in most secondary markets and higher in coastal infill markets, but larger absolute square footage, and terms of three to seven years for smaller bays up to ten-plus years for build-to-suit distribution centers.

Office leases, particularly since 2020, have shifted toward shorter terms (three to seven years is now common versus seven to ten years before), higher TI allowances to win tenants in an oversupplied market, and in many metro submarkets effective rents well below asking rents once concessions are included, a gap landlords describe as the spread between face rent and effective rent.

Comparing only starting base rent across competing proposals. A lower starting rent with weak escalations and no free rent can cost more in total than a higher starting rent with generous concessions once the full term is modeled; effective rent is the only fair comparison.

Underestimating CAM growth. Tenants who anchor their budget to the landlord's initial NNN estimate without adding a growth buffer are routinely surprised by reconciliation bills, especially in the first two years after an ownership change triggers a property tax reassessment.

Treating the TI allowance as free money. Unused TI dollars in many leases are forfeited, not paid to the tenant, and overspending the allowance means the tenant funds the difference in cash. Tenants should get a detailed, competitively bid construction estimate before finalizing the allowance figure in the lease.

Ignoring the amortized TI when a landlord offers to fund improvements above the standard allowance in exchange for a higher rent. That additional TI is effectively a loan repaid through rent, usually amortized at 8% to 12% implied interest, which can be far more expensive than the tenant realizes if it is not modeled explicitly.

Failing to cap CAM increases. Many tenants, particularly in retail, negotiate an annual cap on controllable CAM increases (often 5% per year), which limits the landlord's ability to pass through cost overruns while leaving true pass-throughs like taxes and insurance uncapped.

Not modeling renewal option rent. Lease proposals often quote attractive rent for the primary term while the renewal option rent resets to fair market value, which can be meaningfully higher; long-term occupancy cost planning should include a realistic renewal scenario, not just the primary term numbers.